Graphite: consists of carbon atoms arrayed in a hexagonal pattern in large parallel sheets (individual sheets are known as graphene). Alternate sheets are out of phase with each other so that a carbon atom in one sheet lies in line with the hole at the centre of the hexagonal rings above and below. This is illustrated on the graphite structure page. The sheets can slide across each other (helped by contaminants) giving graphite its lubricating and writing properties. Electrons can travel along the strata making graphite an electrical conductor in a direction parallel with the plates.
The carbon atoms are shown as spheres drawn at their covalent radius (i.e. just touching).